On Jan 10, 2023, at 1:43 AM, Dai Ngo [off-list ref] wrote:

Currently the nfsd-client shrinker is registered and unregistered at
the time the nfsd module is loaded and unloaded. This means after the
nfsd service is shutdown, the nfsd-client shrinker is still registered
in the system. This causes the nfsd-client shrinker to be called when
memory is low even thought nfsd service is not running. This is also
true for the nfsd_reply_cache_shrinker.

This patch moves the register/unregister of nfsd-client shrinker from
module load/unload time to nfsd startup/shutdown time.

Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
---
fs/nfsd/nfs4state.c | 18 ++++++------------
fs/nfsd/nfsctl.c    |  7 +------
fs/nfsd/nfsd.h      |  6 ++----
3 files changed, 9 insertions(+), 22 deletions(-)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 7b2ee535ade8..ee56c9466304 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c

@@ -4421,7 +4421,7 @@ nfsd4_state_shrinker_scan(struct shrinker *shrink, struct shrink_control *sc)

	return SHRINK_STOP;
}

-int
+void
nfsd4_init_leases_net(struct nfsd_net *nn)
{
	struct sysinfo si;

@@ -4443,16 +4443,6 @@ nfsd4_init_leases_net(struct nfsd_net *nn)

	nn->nfs4_max_clients = max_t(int, max_clients, NFS4_CLIENTS_PER_GB);

	atomic_set(&nn->nfsd_courtesy_clients, 0);
-	nn->nfsd_client_shrinker.scan_objects = nfsd4_state_shrinker_scan;
-	nn->nfsd_client_shrinker.count_objects = nfsd4_state_shrinker_count;
-	nn->nfsd_client_shrinker.seeks = DEFAULT_SEEKS;
-	return register_shrinker(&nn->nfsd_client_shrinker, "nfsd-client");
-}
-
-void
-nfsd4_leases_net_shutdown(struct nfsd_net *nn)
-{
-	unregister_shrinker(&nn->nfsd_client_shrinker);
}

static void init_nfs4_replay(struct nfs4_replay *rp)

@@ -8077,7 +8067,10 @@ static int nfs4_state_create_net(struct net *net)

	INIT_DELAYED_WORK(&nn->nfsd_shrinker_work, nfsd4_state_shrinker_worker);
	get_net(net);

-	return 0;
+	nn->nfsd_client_shrinker.scan_objects = nfsd4_state_shrinker_scan;
+	nn->nfsd_client_shrinker.count_objects = nfsd4_state_shrinker_count;
+	nn->nfsd_client_shrinker.seeks = DEFAULT_SEEKS;
+	return register_shrinker(&nn->nfsd_client_shrinker, "nfsd-client");

err_sessionid:
	kfree(nn->unconf_id_hashtbl);

@@ -8171,6 +8164,7 @@ nfs4_state_shutdown_net(struct net *net)

	struct list_head *pos, *next, reaplist;
	struct nfsd_net *nn = net_generic(net, nfsd_net_id);

+	unregister_shrinker(&nn->nfsd_client_shrinker);
	cancel_delayed_work_sync(&nn->laundromat_work);
	locks_end_grace(&nn->nfsd4_manager);

diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c
index d1e581a60480..c2577ee7ffb2 100644
--- a/fs/nfsd/nfsctl.c
+++ b/fs/nfsd/nfsctl.c

@@ -1457,9 +1457,7 @@ static __net_init int nfsd_init_net(struct net *net)

		goto out_idmap_error;
	nn->nfsd_versions = NULL;
	nn->nfsd4_minorversions = NULL;
-	retval = nfsd4_init_leases_net(nn);
-	if (retval)
-		goto out_drc_error;
+	nfsd4_init_leases_net(nn);
	retval = nfsd_reply_cache_init(nn);
	if (retval)
		goto out_cache_error;

@@ -1469,8 +1467,6 @@ static __net_init int nfsd_init_net(struct net *net)

	return 0;

out_cache_error:
-	nfsd4_leases_net_shutdown(nn);
-out_drc_error:
	nfsd_idmap_shutdown(net);
out_idmap_error:
	nfsd_export_shutdown(net);

@@ -1486,7 +1482,6 @@ static __net_exit void nfsd_exit_net(struct net *net)

	nfsd_idmap_shutdown(net);
	nfsd_export_shutdown(net);
	nfsd_netns_free_versions(net_generic(net, nfsd_net_id));
-	nfsd4_leases_net_shutdown(nn);
}

static struct pernet_operations nfsd_net_ops = {

diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 93b42ef9ed91..fa0144a74267 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h

@@ -504,8 +504,7 @@ extern void unregister_cld_notifier(void);

extern void nfsd4_ssc_init_umount_work(struct nfsd_net *nn);
#endif

-extern int nfsd4_init_leases_net(struct nfsd_net *nn);
-extern void nfsd4_leases_net_shutdown(struct nfsd_net *nn);
+extern void nfsd4_init_leases_net(struct nfsd_net *nn);

#else /* CONFIG_NFSD_V4 */
static inline int nfsd4_is_junction(struct dentry *dentry)

@@ -513,8 +512,7 @@ static inline int nfsd4_is_junction(struct dentry *dentry)

	return 0;
}

-static inline int nfsd4_init_leases_net(struct nfsd_net *nn) { return 0; };
-static inline void nfsd4_leases_net_shutdown(struct nfsd_net *nn) {};
+static inline void nfsd4_init_leases_net(struct nfsd_net *nn) { };

#define register_cld_notifier() 0
#define unregister_cld_notifier() do { } while(0)
-- 
2.9.5